1. Field of the Invention
Present invention relates to a method for driving a liquid drop ejecting head for ejecting a liquid drop from an ejecting section by driving a piezoelectric transducer by a predetermined driving waveform. In particular, the present invention relates to a device for driving a liquid drop ejecting head for generating a driving waveform by combining line-segmented-waveforms which are contained in a memory, a device for forming a membrane, a method for driving a liquid drop ejecting head, a method for forming a membrane, and a method for manufacturing an electronic apparatus and a device.
2. Description of Related Art
A liquid drop ejecting head which vibrates a transducer for ejecting a liquid drop by expanding and contracting the piezoelectric transducer is used in a liquid drop ejecting device which is called an ink jet printer which is used for a manufacturing device for a liquid crystal display panel and a printing device of a computer terminal. The piezoelectric transducer is formed by, for example, a piezo (PZT)-element. The piezo-element expands and contracts a driving waveform which is inputted thereto (for example, a voltage waveform).
In a device for driving a liquid drop ejecting head having such a structure, the piezoelectric transducer is driven by an approximate trapezoid square voltage waveform shown in FIG. 16. For example, an electric potential Vcom in the drawing is a predetermined voltage which is charged to the piezoelectric transducer. An electric potential VH indicates a voltage value for most contracting the piezoelectric transducer in a liquid drop ejecting direction. Also, an electric potential VL indicates a voltage value for most expanding the piezoelectric transducer in a liquid drop ejecting direction. A layered piezo-element contracts most in a liquid drop ejecting direction when a charged voltage is at an electric potential VL. The layered piezo-element is released from the contraction and expands when a charged voltage is at an electric potential VL. That is, the piezo-element is displaced in a liquid drop ejecting direction by an inertia over a displacement value 0 which indicates a static condition. A liquid drop ejecting device ejects a liquid drop by a piezoelectric transducer which expands and contracts.
Also, a driving waveform shown in FIG. 16 is generated by, for example, a D/A converter. Here, a driving waveform ascends stepwise at it output end by a constant voltage ΔV per a unit time ΔT as shown in a magnified manner in FIG. 17. Such a conventional liquid drop ejecting device for ejecting a liquid drop by driving a piezoelectric transducer by using a driving waveform is disclosed in a patent document 1, for example, Japanese Unexamined Patent Application, First Publication No. 2002-059614.
By the way, the piezoelectric transducer repeats physical operations such as expansion and contraction; therefore, an element itself becomes worn and deteriorated. Also, it is known that the element becomes deteriorated sooner and its fatigue life becomes shorter due to factors such as an increase in a thermal load because of a rapid expansion and contraction and an increase in a physical load because of a rapid transition between an expansion/contraction condition and a static condition.
In addition, in a device for driving a liquid drop ejecting head in a conventional technology, the piezoelectric transducer is driven by a trapezoid wave as shown in FIG. 16; therefore, operational status of the piezoelectric transducer alters rapidly in points A0 to A5 in the waveform. Therefore, as explained above, more load is applied to the piezoelectric transducer physical and thermally; thus, there has been a problem in that the element becomes deteriorated sooner and it is not possible to eject a liquid drop from the liquid drop ejecting head stably in a longer time.